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8049421: G1 Class Unloading after completing a concurrent mark cycle

Browse source 
Co-authored-by: Mikael Gerdin <mikael.gerdin@oracle.com>
Reviewed-by: tschatzl, ehelin, brutisso, coleenp, roland, iveresov
This commit is contained in:
Stefan Karlsson 2014-07-07 10:12:40 +02:00
parent ef1e9b3c80
commit 1b001a2afd
75 changed files with 2169 additions and 874 deletions
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331
hotspot/src/share/vm/code/nmethod.cpp
View file

@ -51,6 +51,8 @@
PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
unsigned char nmethod::_global_unloading_clock = 0;
#ifdef DTRACE_ENABLED
// Only bother with this argument setup if dtrace is available
@ -446,6 +448,7 @@ const char* nmethod::compile_kind() const {
// Fill in default values for various flag fields
void nmethod::init_defaults() {
_state = in_use;
_unloading_clock = 0;
_marked_for_reclamation = 0;
_has_flushed_dependencies = 0;
_has_unsafe_access = 0;
@ -464,7 +467,11 @@ void nmethod::init_defaults() {
_oops_do_mark_link = NULL;
_jmethod_id = NULL;
_osr_link = NULL;
_scavenge_root_link = NULL;
if (UseG1GC) {
_unloading_next = NULL;
} else {
_scavenge_root_link = NULL;
}
_scavenge_root_state = 0;
_compiler = NULL;
#if INCLUDE_RTM_OPT
@ -1170,6 +1177,77 @@ void nmethod::cleanup_inline_caches() {
}
}
void nmethod::verify_clean_inline_caches() {
assert_locked_or_safepoint(CompiledIC_lock);
// If the method is not entrant or zombie then a JMP is plastered over the
// first few bytes. If an oop in the old code was there, that oop
// should not get GC'd. Skip the first few bytes of oops on
// not-entrant methods.
address low_boundary = verified_entry_point();
if (!is_in_use()) {
low_boundary += NativeJump::instruction_size;
// %%% Note: On SPARC we patch only a 4-byte trap, not a full NativeJump.
// This means that the low_boundary is going to be a little too high.
// This shouldn't matter, since oops of non-entrant methods are never used.
// In fact, why are we bothering to look at oops in a non-entrant method??
}
ResourceMark rm;
RelocIterator iter(this, low_boundary);
while(iter.next()) {
switch(iter.type()) {
case relocInfo::virtual_call_type:
case relocInfo::opt_virtual_call_type: {
CompiledIC *ic = CompiledIC_at(&iter);
// Ok, to lookup references to zombies here
CodeBlob *cb = CodeCache::find_blob_unsafe(ic->ic_destination());
if( cb != NULL && cb->is_nmethod() ) {
nmethod* nm = (nmethod*)cb;
// Verify that inline caches pointing to both zombie and not_entrant methods are clean
if (!nm->is_in_use() || (nm->method()->code() != nm)) {
assert(ic->is_clean(), "IC should be clean");
}
}
break;
}
case relocInfo::static_call_type: {
CompiledStaticCall *csc = compiledStaticCall_at(iter.reloc());
CodeBlob *cb = CodeCache::find_blob_unsafe(csc->destination());
if( cb != NULL && cb->is_nmethod() ) {
nmethod* nm = (nmethod*)cb;
// Verify that inline caches pointing to both zombie and not_entrant methods are clean
if (!nm->is_in_use() || (nm->method()->code() != nm)) {
assert(csc->is_clean(), "IC should be clean");
}
}
break;
}
}
}
}
int nmethod::verify_icholder_relocations() {
int count = 0;
RelocIterator iter(this);
while(iter.next()) {
if (iter.type() == relocInfo::virtual_call_type) {
if (CompiledIC::is_icholder_call_site(iter.virtual_call_reloc())) {
CompiledIC *ic = CompiledIC_at(&iter);
if (TraceCompiledIC) {
tty->print("noticed icholder " INTPTR_FORMAT " ", p2i(ic->cached_icholder()));
ic->print();
}
assert(ic->cached_icholder() != NULL, "must be non-NULL");
count++;
}
}
}
return count;
}
// This is a private interface with the sweeper.
void nmethod::mark_as_seen_on_stack() {
assert(is_alive(), "Must be an alive method");
@ -1202,6 +1280,23 @@ void nmethod::inc_decompile_count() {
mdo->inc_decompile_count();
}
void nmethod::increase_unloading_clock() {
_global_unloading_clock++;
if (_global_unloading_clock == 0) {
// _nmethods are allocated with _unloading_clock == 0,
// so 0 is never used as a clock value.
_global_unloading_clock = 1;
}
}
void nmethod::set_unloading_clock(unsigned char unloading_clock) {
OrderAccess::release_store((volatile jubyte*)&_unloading_clock, unloading_clock);
}
unsigned char nmethod::unloading_clock() {
return (unsigned char)OrderAccess::load_acquire((volatile jubyte*)&_unloading_clock);
}
void nmethod::make_unloaded(BoolObjectClosure* is_alive, oop cause) {
post_compiled_method_unload();
@ -1247,6 +1342,10 @@ void nmethod::make_unloaded(BoolObjectClosure* is_alive, oop cause) {
// for later on.
CodeCache::set_needs_cache_clean(true);
}
// Unregister must be done before the state change
Universe::heap()->unregister_nmethod(this);
_state = unloaded;
// Log the unloading.
@ -1590,6 +1689,35 @@ void nmethod::post_compiled_method_unload() {
set_unload_reported();
}
void static clean_ic_if_metadata_is_dead(CompiledIC *ic, BoolObjectClosure *is_alive) {
if (ic->is_icholder_call()) {
// The only exception is compiledICHolder oops which may
// yet be marked below. (We check this further below).
CompiledICHolder* cichk_oop = ic->cached_icholder();
if (cichk_oop->holder_method()->method_holder()->is_loader_alive(is_alive) &&
cichk_oop->holder_klass()->is_loader_alive(is_alive)) {
return;
}
} else {
Metadata* ic_oop = ic->cached_metadata();
if (ic_oop != NULL) {
if (ic_oop->is_klass()) {
if (((Klass*)ic_oop)->is_loader_alive(is_alive)) {
return;
}
} else if (ic_oop->is_method()) {
if (((Method*)ic_oop)->method_holder()->is_loader_alive(is_alive)) {
return;
}
} else {
ShouldNotReachHere();
}
}
}
ic->set_to_clean();
}
// This is called at the end of the strong tracing/marking phase of a
// GC to unload an nmethod if it contains otherwise unreachable
// oops.
@ -1633,31 +1761,7 @@ void nmethod::do_unloading(BoolObjectClosure* is_alive, bool unloading_occurred)
while(iter.next()) {
if (iter.type() == relocInfo::virtual_call_type) {
CompiledIC *ic = CompiledIC_at(&iter);
if (ic->is_icholder_call()) {
// The only exception is compiledICHolder oops which may
// yet be marked below. (We check this further below).
CompiledICHolder* cichk_oop = ic->cached_icholder();
if (cichk_oop->holder_method()->method_holder()->is_loader_alive(is_alive) &&
cichk_oop->holder_klass()->is_loader_alive(is_alive)) {
continue;
}
} else {
Metadata* ic_oop = ic->cached_metadata();
if (ic_oop != NULL) {
if (ic_oop->is_klass()) {
if (((Klass*)ic_oop)->is_loader_alive(is_alive)) {
continue;
}
} else if (ic_oop->is_method()) {
if (((Method*)ic_oop)->method_holder()->is_loader_alive(is_alive)) {
continue;
}
} else {
ShouldNotReachHere();
}
}
}
ic->set_to_clean();
clean_ic_if_metadata_is_dead(ic, is_alive);
}
}
}
@ -1695,6 +1799,175 @@ void nmethod::do_unloading(BoolObjectClosure* is_alive, bool unloading_occurred)
verify_metadata_loaders(low_boundary, is_alive);
}
template <class CompiledICorStaticCall>
static bool clean_if_nmethod_is_unloaded(CompiledICorStaticCall *ic, address addr, BoolObjectClosure *is_alive, nmethod* from) {
// Ok, to lookup references to zombies here
CodeBlob *cb = CodeCache::find_blob_unsafe(addr);
if (cb != NULL && cb->is_nmethod()) {
nmethod* nm = (nmethod*)cb;
if (nm->unloading_clock() != nmethod::global_unloading_clock()) {
// The nmethod has not been processed yet.
return true;
}
// Clean inline caches pointing to both zombie and not_entrant methods
if (!nm->is_in_use() || (nm->method()->code() != nm)) {
ic->set_to_clean();
assert(ic->is_clean(), err_msg("nmethod " PTR_FORMAT "not clean %s", from, from->method()->name_and_sig_as_C_string()));
}
}
return false;
}
static bool clean_if_nmethod_is_unloaded(CompiledIC *ic, BoolObjectClosure *is_alive, nmethod* from) {
return clean_if_nmethod_is_unloaded(ic, ic->ic_destination(), is_alive, from);
}
static bool clean_if_nmethod_is_unloaded(CompiledStaticCall *csc, BoolObjectClosure *is_alive, nmethod* from) {
return clean_if_nmethod_is_unloaded(csc, csc->destination(), is_alive, from);
}
bool nmethod::do_unloading_parallel(BoolObjectClosure* is_alive, bool unloading_occurred) {
ResourceMark rm;
// Make sure the oop's ready to receive visitors
assert(!is_zombie() && !is_unloaded(),
"should not call follow on zombie or unloaded nmethod");
// If the method is not entrant then a JMP is plastered over the
// first few bytes. If an oop in the old code was there, that oop
// should not get GC'd. Skip the first few bytes of oops on
// not-entrant methods.
address low_boundary = verified_entry_point();
if (is_not_entrant()) {
low_boundary += NativeJump::instruction_size;
// %%% Note: On SPARC we patch only a 4-byte trap, not a full NativeJump.
// (See comment above.)
}
// The RedefineClasses() API can cause the class unloading invariant
// to no longer be true. See jvmtiExport.hpp for details.
// Also, leave a debugging breadcrumb in local flag.
bool a_class_was_redefined = JvmtiExport::has_redefined_a_class();
if (a_class_was_redefined) {
// This set of the unloading_occurred flag is done before the
// call to post_compiled_method_unload() so that the unloading
// of this nmethod is reported.
unloading_occurred = true;
}
// Exception cache
clean_exception_cache(is_alive);
bool is_unloaded = false;
bool postponed = false;
RelocIterator iter(this, low_boundary);
while(iter.next()) {
switch (iter.type()) {
case relocInfo::virtual_call_type:
if (unloading_occurred) {
// If class unloading occurred we first iterate over all inline caches and
// clear ICs where the cached oop is referring to an unloaded klass or method.
clean_ic_if_metadata_is_dead(CompiledIC_at(&iter), is_alive);
}
postponed |= clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);
break;
case relocInfo::opt_virtual_call_type:
postponed |= clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);
break;
case relocInfo::static_call_type:
postponed |= clean_if_nmethod_is_unloaded(compiledStaticCall_at(iter.reloc()), is_alive, this);
break;
case relocInfo::oop_type:
if (!is_unloaded) {
// Unload check
oop_Relocation* r = iter.oop_reloc();
// Traverse those oops directly embedded in the code.
// Other oops (oop_index>0) are seen as part of scopes_oops.
assert(1 == (r->oop_is_immediate()) +
(r->oop_addr() >= oops_begin() && r->oop_addr() < oops_end()),
"oop must be found in exactly one place");
if (r->oop_is_immediate() && r->oop_value() != NULL) {
if (can_unload(is_alive, r->oop_addr(), unloading_occurred)) {
is_unloaded = true;
}
}
}
break;
}
}
if (is_unloaded) {
return postponed;
}
// Scopes
for (oop* p = oops_begin(); p < oops_end(); p++) {
if (*p == Universe::non_oop_word()) continue; // skip non-oops
if (can_unload(is_alive, p, unloading_occurred)) {
is_unloaded = true;
break;
}
}
if (is_unloaded) {
return postponed;
}
// Ensure that all metadata is still alive
verify_metadata_loaders(low_boundary, is_alive);
return postponed;
}
void nmethod::do_unloading_parallel_postponed(BoolObjectClosure* is_alive, bool unloading_occurred) {
ResourceMark rm;
// Make sure the oop's ready to receive visitors
assert(!is_zombie(),
"should not call follow on zombie nmethod");
// If the method is not entrant then a JMP is plastered over the
// first few bytes. If an oop in the old code was there, that oop
// should not get GC'd. Skip the first few bytes of oops on
// not-entrant methods.
address low_boundary = verified_entry_point();
if (is_not_entrant()) {
low_boundary += NativeJump::instruction_size;
// %%% Note: On SPARC we patch only a 4-byte trap, not a full NativeJump.
// (See comment above.)
}
RelocIterator iter(this, low_boundary);
while(iter.next()) {
switch (iter.type()) {
case relocInfo::virtual_call_type:
clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);
break;
case relocInfo::opt_virtual_call_type:
clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);
break;
case relocInfo::static_call_type:
clean_if_nmethod_is_unloaded(compiledStaticCall_at(iter.reloc()), is_alive, this);
break;
}
}
}
#ifdef ASSERT
class CheckClass : AllStatic {
@ -1911,7 +2184,7 @@ void nmethod::oops_do_marking_epilogue() {
assert(cur != NULL, "not NULL-terminated");
nmethod* next = cur->_oops_do_mark_link;
cur->_oops_do_mark_link = NULL;
cur->fix_oop_relocations();
cur->verify_oop_relocations();
NOT_PRODUCT(if (TraceScavenge) cur->print_on(tty, "oops_do, unmark"));
cur = next;
}
@ -2479,6 +2752,10 @@ public:
};
void nmethod::verify_scavenge_root_oops() {
if (UseG1GC) {
return;
}
if (!on_scavenge_root_list()) {
// Actually look inside, to verify the claim that it's clean.
DebugScavengeRoot debug_scavenge_root(this);